Ethylenically unsaturated esters of azobenzene



3,196,874 ETHYLENHCALLY UNSATEIRATED ESTERS (BF AZOBENZENE Martin M. Sikoultchi, New York, N.Y., Albert 1. Goldberg, Berkeley Heights, NJ., and .loseph Fertig, New York, N .Y., assignors to National Starch and Chemical Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Apr. 19, 1962, Ser. No. 188,861

6 Claims. (Cl. zen-19s This invention relates to the preparation of novel ethylenically unsaturated derivatives of azobenzene, and more particularly to ethylenically unsaturated esters of azobenzenes.

It is the object of this invention to produce a novel class of ethylenically unsaturated azobenzene derivatives which are capable of undergoing vinyl type polymerization reactions either alone or in the presence of other vinyl type comonomers. A further object of this invention involves the preparation of polymerizable azobenzene derivatives which can be incorporated into a wide variety of polymers and copolymers so as to provide such polymers with a permanent, integral color as well as with improved light stability.

As is well known in the art, a vast number of the derivatives of azobenzene, i.e. derivatives of are employed as dyes and coloring agents. These compounds, which are collectively referred to as azo dyes, have had extensive application, particularly in the textile industry, wherein they have long been successfully used for the dyeing of naturally derived fibers and fabrics, such as those made from wool, cotton, silk and linen, as. well as of artificial cellulosic fibers and fabrics, such as those made from rayon and various cellulose esters. However, with the advent and ever increasing popularity of the purely synthetic fibers, such as those derived, for example, from polyacrylic, polyester, polyvinyl chloride, polyvinylidene chloride, and polyolefin resins, it was found that many azo dyes, as well as many other existing dyes and dyeing techniques, were no longer operable with these new synthetic resin based fibers. As a result, it became necessary to devise new dyes and dyeing techniques for these materials. Moreover, dyes, in general, cannot be used for the permanent coloring of the films, sheets, and molded products which are made from such synthetic resins since such conversion products can be colored only by the inclusion, therein, of extraneous pigments.

The novel compositions of our invention are the ethylenically unsaturated azobenzene derivatives corresponding to the formula:

wherein R and R are radicals of the benzene series selected from among the group consisting of phenyl and naphthyl radicals and wherein Z is an ethylenically unsaturated group selected from among the class consisting of beta-hydroxypropyl acrylate and beta-hydroxypropyl methacrylate groups and X and Y represent at least one member selected from among the group consisting of hydrogen, alkyl, aryl, acyloxy, aralkyl, alkoxy, hydroxy or halogen radicals.

The following list is representative of the azobenzene derivatives of our invention. For purposes of brevity,

, United States Patent 3,i%,874 Patented June 22, 1965 ICC this list notes only the beta-hydroxypropyl methacrylate derivatives; however, it is, of course, to be understood that the corresponding beta-hydroxypropyl acrylate derivatives may also be prepared. One may thus list: 2-hydroxy-3- S-phenylazo-2-hydroxybenzoyloxy propyl methacrylate; 2 hydroxy-S (4-phenylazobenzoyloxy)propyl methacrylate; 2-hydroxy-3 (2 phenylazobenzoyloxy)- propyl methacrylate; Z-hydroxy 3 (4-[4-rnethylphenylazo]benzoyloxy) propyl methacrylate; 2-hydroxy-3-(5- [4- rnethylphenylazo] Z-hydroxybenzoyloxy)propyl methacrylate; 2-hydroXy-3-(5-[3-rnethylphenylazo] 2 hydroxy benzoyloxyj propyl methacrylate; 2-hydroxy-3- 5- [Z-methylphenylazo] -2-hydroxybenzoyloxy) propyl methacrylate; 2-hydroxy-3-(4[2 chlorophenylazo]benzoyloxy)propyl methacrylate; 2-hydroxy-3- (4- Z-methoxyphenylazo] benzoyloxy)propyl methacrylate; 2-hydrcxy-3-(4-[4-phenylphenylazo]benz0yloxy)propyl methacrylate; and, 2 hydroxy-3-(4- [2 naphthylazo1benzoyloxy) propyl methacrylate.

Thus, the novel azobenzene derivatives of our invention,

wherein R is a radical of the benzene series selected from the group consisting of phenyl and naphthyl radicals, wherein R is a phenyl radical, wherein Q is a radical selected from the group consisting of hydrogen and methyl radicals, and wherein X and Y represent hydrogen.

Thus, it is to be seen that the derivatives of our invention may be referred to as the beta-hydroxypropyl acrylate and the beta-hydroxy propyl metharcrylate esters of azobenzene. Each of the above listed derivatives, along with any others which may be prepared by the practitioner, may, in turn, contain a variety of other substituent groups including aikyl, aryl, acyloxy, aralkyl, alkoxy, hydroxy and halogen groups wherein any one, or more, of these substituent groups may be substituted upon any available position in one or both of the phenyl rings in the azobenzene nucleus. Moreover, it is this ability to prepare our novel derivatives so that they may contain one or more of these various substituent groups on any position in the azobenzene nucleus, which permits our derivatives to possess any desired shading of primary color.

All of the above listed compounds, as well as any others which may correspond to the above described formula, are materials which are capable of readily undergoing vinyl type polymerization. They are thus useful for the preparation of homopolymers and, more particularly, for the preparation of copolymers with a wide variety of other vinyl type, i.e. ethylenically unsaturated, monomers. Such copolymers have a built in color and also possess superior light stability, both of the latter properties being imparted 'to these copolymers as a result of the presence therein of the azobenzene moiety which is permanently bound into and inherently part of the resulting copolymer molecule as a result of the incorporation therein of the ethylenically unsaturated azobenzene derivatives of our invention. The use, in this manner, of these derivatives is thus seen to overcome the inadequacies of azo and other heretofore utilized dyes with respect to their unsuccessful use in the dyeing of fibers and fabrics, as well as for the coloring of films, sheets, and moldings derived from any of the synthetic resins which are prepared, either in whole or in part, from one or more ethylenically unsaturated monomers.

In brief, the synthesis of our novel derivatives is accomplished by the catalyzed reaction of either glycidyl acrylate or glycidyl methacrylate with a carboxylated azobenzene or substituted carboxylated azobenzene intermediate. This reaction thus yields either the beta-hydroxypropyl methacrylate or the beta-hydroxypropyl acrylate ester of azobenzene or of the substituted azobenzene intermediate. Hereinafter it is to be understood that the use, for purposes of brevity, of the expression, the carboxylated azobenzene intermediate is meant to include any carboxylated azobenzene as Well as any substituted carboxylated azobenzene intermediate applicable for use in the process of our invention.

In conducting the above described reaction, the glycidyl acrylate or methacrylate, in a concentration amounting to a slight stoichiometric excess in the order of about to over the subsequently added carboxylated azobenzene intermediate, is first ordinarily admixed with the selected catalyst. The latter may be selected from among any member of the group consisting of the alkali metal hydroxides, such as sodium hydroxide or potassium hyroxide; and the basic salts of the alkali metals, such as sodium bicarbonate or sodium carbonate. These catalysts should be present in a concentration in the range of about 0.1 to 5.0%, as based upon the weight of the glycidyl arcylate or methacrylate.

To this mixture, comprising the catalyst and the glycidyl acrylate or methacrylate, there is then added, with continued agitation, and preferably on a portionwise basis, the selected carboxylated azobenzene intermediate. Such portionwise addition, which may be either continuous or intermittent, is preferred in the process of our invention since these carboxylated azobenzene intermediates are, for the most part, either low melting solids or highly viscous oils. Thus, if they were to be completely added at the initiation of the reaction, they would promptly absorb the bulk of the glycidyl acrylate or methacrylate, thereby resulting is a solid, heterogeneous mass which is rather ditlicult to mix. However, by adding these intermediates on a portionwise basis, the reaction mixture is, instead, readily maintained in a fluid, mixable state.

In those cases wherein the ultimate ethylenically unsaturated azobenzene derivative is known to undergo spontaneous homopolymerization, there may also be added to the reaction mixture from about 0.001 to about 0.1%, as based upon the initial weight of the carboxylated azobenzene intermediate, of a polymerization inhibitor such as benzoquinone or hydroquinone or its monomethyl ether.

Following the complete addition of the carboxylated azobenzene intermediate to the mixture of the catalyst and the glycidyl acrylate or methacrylate, agitation is continued while the reaction mixture is maintained at a temperature in the range of about 50 to 100 C., and preferably at about 70 to 80 C., for periods of about 6 to 8 hours. Under these conditions, the reaction between the glycidyl acrylate or methacrylate and the carboxylated azobenzene intermediate will ordinarily proceed to about 85 to 95% of the calculated theoretical yield.

In general, it should be noted that the reaction can be conducted at any temperature which will be high enough so as to result in an adequate reaction rate but which will not be so high as to cause the spontaneous polymerization of the resulting ethylenically unsaturated azobenzene derivative. In addition the length of the reaction period which will be required for the attainment of high yields will depend, for the most part, upon the specific carboxylated azobenzene intermediate which is being utilized. Thus, it is a matter of simple experimentation on the part of the practitioner to determine the precise combination of time and temperature which will be best suited for the synthesis of any of the novel azobenzene derivatives coming within the scope of our invention.

Upon the completion of the reaction, the resulting prodnet will ordinarily solidify upon being allowed to cool to room temperature. For most purposes, including any subsequent polymerization reactions, this crude beta-hydroxypropyl acrylate or methacrylate ester of azobenzene can then be used Without any further purification being necessary. However, where desired, the relatively small amount of unreactcd carboxylated azobenzene intermediate may be removed. Thus, such means as chromatographic separation tcchniques, as for example with the use of a silica gel column, have been found to yield a product which, by means of saponification equivalent, will indicate a purity of by Weight. Other separation techniques, such as alkaline or organic solvent extraction procedures, may also be used where so desired by the practitioner.

It is also possible, where so desired, to prepare the novel derivatives of our invention by reaction in an organic solvent medium. Under these conditions, the carboxylated azobenzene intermediate, the catalyst, and the glycidyl acrylate or methacrylate may all be dissolved in a non-reactive polar solvent such as acetone, methyl ethyl ketone, or butyl acetate. The resulting derivative would then be recovered by distilling ed the solvent whereupon the crude product could, again, be purified by means of any of the above noted techniques.

The intermediates for the above described process, is. the various applicable carboxylated azobenzene compounds, are commercially available materials which are prepared by means of reactions well known to those skilled in the art. These reactions involve either the coupling of a carboxylated phenyldiazonium halide together with an appropriately substituted phenol or the coupling of a phenyldiazonium halide, or appropriately substituted phenyldiazonium halide, together with a selected carboxylated phenol. Thus, by starting with such substituted phenols or substituted phenyldiazonium salts, it is of course possible to prepare the ultimate beta-hydroxy acrylate or methacrylate ester of azobenzene with a variety of alkyl, aryl, acyloxy, aralkyl, alkoxy, hydroxy or halogen radical substituents wherein said substituent radicals may be on either one or both of the phenyl rings of the azobenzene nucleus. By varying the structure of the intermediate in this manner, it is possible, as noted earlier, to prepare our ethylenically unsaturated azobenzene derivatives so that they may inherently possess any shading of primary color which may be selected by the practitioner. This, in turn, permits the copolymers which can be prepared with the use of our derivatives as comonomers to be made in any desired permanent color without the need for blending with extraneous pigments. It is to be noted, at this point, that the initial preparation of the carboxylated azobenzene intermediates does not constitute a novel aspect of the process of our invention.

The following examples will further illustrate the embodiment of this invention. In these examples, all parts given are by weight unless otherwise noted.

Example I This example illustrates the preparation of 2-hydroxy- 3-(5 phenylazo-Z hydroxybenzoyloxy)propyl methacrylate, i.e.

by means of the process of our invention.

To an agitated mixture of 156 parts of glycidyl methacrylate and 3.2 parts of a 50%, by weight, aqueous solution of sodium hydroxide, there were added on an intermittent, portionwise basis, 242 parts of 5-phenylazo-2- hydroxybenzoie acid. During the addition of the latter carboxylated azobenzene intermediate, agitation was continned and the temperature of the reaction mixture was brought to a level in the range of 70-80" C. The addition of this carboxylated azobenzene intermediate took 1 hour whereupon the reaction mixture was maintained,

6 In preparing this product, we employed the identical procedure as was utilized for the preparation of the derivative of Example I with the exception that 141 parts of glycidyl acrylate were, in this case, used in place of the under agitation, for an additional 7 hours period at .a tem 5 156 parts of glycidyl methacrylate of Example I. This perature in the range of 70-80" C. procedure produced 368parts, or about 94% of the theo- Upon being cooled to room temperature, i.e. 25 C., retical yield, of solid Z-hydroxy-B-(5-phenylazo-2-hydr0xythe resulting reaction product solidified. Analysis of the henzoyloxy)propyl acrylate. This solid product, a1- crude material, for the presence of any unreacted carthough tan in color, yielded yellow-orange solutions when boxylated azobenzene intermediate, indicated a yield of 10 dissolved in organic solvents such as acetone. 383 parts of the 2-hydr0Xy-3-(5-phenylazo-2-hydroxyben- E l [H zoyloxy) propyl methacrylate which was in the order of I I xamp e 9 by weight, Ofthe h ore T is l d pr uct, The following table presents the pertinent data relating although tan in color, yielded yellow-orange solutions to 20 additional ethylenically unsaturated azobenzene de- When dissolved in organic solvents such as acetone. rivatives. In this table, derivatives Nos. 1, '3, 5, 7, 9, 11, 1.3, 15, 17, and 19, i.e. the odd numbered derivatives, are Example H heta-hydroxypropyl methacrylate esters of azobenzene This example illustrates the preparation of 2-hydroxy-3- S2 E g i gg gj zgg 23 i ig 2 3 3 3? 1 r 1 2 .v a 1 1 r (5 phenylazo 2 hydroxybenzoy oxwpropy acrylate 1 e 20, i.e. the even numbered derivatives are beta-hydroxy- OH propyl acrylate esters of azobenzene which were prepared E by means of the procedure of Example II. In the struc- .tural formulas which are given for each of these deriv- OCH CH-CH 0 CH=OH II 2 atives, the abbreviations HPMA and HPA are used, 0 0H 25 respectively, to designate rbeta-hydroXypr-opyl methacryby means of the process of our invention. late and beta-hydroxypropyl acrylate groups.

Parts Color of azoben- Yield Yield organic No. Name Structure zene (percent, pts. solvent interby wt.) by wt.) solution med1ate* 1 Zhydroxy-Zt-(-phenylazo- -N=NCOHPMA 226 93 361 Yellow.

benzoyloxy)propyl meth- H I acrylate. '0

2 2-hydr0xy-3-(4-phenylaz0- N= -conm 22s 94 351 Do.

benz0yloxy)propy1 acrylate. g

3 2-hydr0xy-3-(2-phenylazo- N=N- COHPMA 226 313 Do.

benzoyloxy)propyl meth- H acrylate. 0

4 2-hydr0xy-3-(2-phenylaz0- -N=N- ---C0HPA 226 83 '312 Do.

benzoyloxy)propylacrylate. p

5 Z-hydroxy-H-(4-[4-methy1- CH;N=NCO 240 92 370 Do. phenylazo]benzoyloxy)- H l propyl methacrylate. 0 HPMA 6 2-hydroxy-3-(4-[4-methyl- OHS-4 N=N- oo 240 92.5 359 D0.

phenylaz0]benz0y10xy)- H I propyl acrylate. HPA

7 2-hydroxy-3-(5-[4-methyl- CH -N=NOH 256 94.5 396 Orange.

ghenylitzo]-)2-hgdrtfxyth I 61120 0}; 1 m acrylaie yp py (II-OHPMA s 2-hydroxy-3-(5-[4-methyl- CHa-N=NOH 256 95 324 Do.

Iphenyl'itzo]-)z-hydrtlnxy- I I6 I y WP W Y fi 2-hydroxy-3-(5-[3-methyl- -N=N-0H 25s 95 39s 4 Do.

Iphenylpzoljl-hydrtfxy-th I I GU20 0X TO 1116 acryla t e. y p Dy CH; (IJ-OHPMA I I I O 10 2-hydroxy-3-(5-[3-methyl- N=N-0H 25s 95 384 Do.

gheny1zI1z0]-)2-hydr l:xy- I I I I 8H 0 O I'O act 21 e.

Z y xyp W Y 0H3 (I3-0HPA See footnote at end of table.

ll..- 2-hydroxy-3-(5-[2-methyl- N=N-0H 25s 95 398 Do.

ghenylaz01-2-hydroxy- I 16 2-hydroxy-3-(4-[2-methoxy- N=N C- O -HPA 256 83 338 Do.

phenylazo]benzoyloxy)- I g Parts Color of azoben- Yield Yield organic No. Name Structure zene (percent, (pts. solvent interby wt.) by wt.) solution mediate enzoyloxy)propy1 methacrylate. (/OHPMA benzoyloxy)propyl acrylate.

OHPA

13... 2-hydroxy-3-(4-[2-ehloro- N=NCOHPMA 260.5 85 362 D0.

pheny1azo]benzoy1oxy)- ll propyl methacrylate. I

14... 2-hydroxy-3-(4-[2-chloro- N=N-CO-HPA 260.5 89 365 Do. phenylazo]benzoyloxy)- ll propyl acrylate. l 0

--. 2-hydroxy-3-(4J2-methoxy- -N=NCOHPMA 256 so 362 Bed.

phenylazo]benzoyloxy)- H propyl methacrylate. O

propyl acrylate.

OCH;

17 2-hydroxy3-(4-[4-phenyl- N=N-C-0HPMA 302 83 378 Yellow.

phenylazo]benzoyloxy)- propyl mothacrylate. O

y yfi-( l p y N= Q-C-O-HPA 302 75 344 Do.

phenylazo]benzoyloxy)- H propyl acrylate. O

20.. 2-hydroxy-3-(4-[2-naphthyl- =N-C-O-HPA 276 92 396 Do.

azo]benzoyloxy)propyl ll acrylate. O

The intermediates used [or the preparation of the above described derivatives are listed below.

Derivative No: Intermediate Summarizing, our invention is thus seen to provide a 1 4-phenylazobenzo1c acid. novel class of ethylenically unsaturated derivatives of 2 Do. azobenzene. Variations may be made in proportions, 2P13enyliizob$112016acldprocedures and materials without departing from the scope of this invention as defined by the following claims. 5 4-(4-methylphenylazo)benzoic acid. We claim;

1. An ethylenicall unsaturated azobenzene derivative 7 5-(4 methylphenylazo) 2 hydroxybenzoic Corresponding to formula:

acid. 8---- Do. 9 5-(3 methylphenylazo) 2 hydroxybenzoic acid. 10 Do. YR N=NR A OCH,CHCH -OOC=OH, 11 5-(2 ;1methylphenylazo) 2 hydroxybenzoic g; 6 1% i ac1 12 Do. 13--- 4-(2-chlorophenylazo)benzoic acid. wherein R is a radical of the benzene series selected 15 4-(Z-methoxyphenylazo)benzoic acid. 7 fr m the group consisting of phenyl and naphthyl radi- 16 D cals, wherein R is a phenyl radical, wherein Q is a radi- 17 4-(4-phenylphenylazo)benzoic acid, cal selected from the group consisting of hydrogen and 18 Do, methyl radicals, and wherein X is a substituent radical se- 19 4-(2-naphthylazo)benzoic acid. lected from the group consisting of hydrogen and hydroxy 20 Do. radicals and wherein Y is a substituent radical selected 9 10 from the group consisting of hydrogen, hydroxy, methyl, 5. 2-hydroxy-3-(4 [2 chlorophenylazo] benzoyloxy) chloro, methoxy and phenyl radicals. propyl acrylate.

2. 2-l1ydroxy-3-(5-phenylazo 2 hydroxybenzoyloxy) 6. 2-hydroxy-3-(4-[2 naphthylazo1benzoy1oxy)propyl propyl acrylate. acrylate.

3. 2-hydroxy-3-(4-phenylazobenzoyloxy) propyl acry- 5 No references cited.

late.

4. 2-hydroxy-3-(5 [4 methy1phenylaz0]2 hydroxy- CHARLES B. PARKER, Primary Examiner. benzoyloxy)propyl acrylate. 

1. AN ETHYLENICALLY UNSATURATED AZOBENZENE DERIVATIVE CORRESPONDING TO THE FORMULA: 